When nitrite levels in the blood went down after using mouthwash, blood pressure went up, and this connection was strong enough to be statistically significant.

When bacteria that help convert nitrate to nitrite in the mouth are reduced, blood pressure tends to go up by a small amount (2-3.5 mmHg for systolic and 2-2.2 mmHg for diastolic).

Bacteria in the mouth help regulate blood pressure by converting nitrate to nitrite, which is part of the body's natural blood pressure control system.

Even when people ate a diet low in nitrate, using the special mouthwash still increased their blood pressure, which suggests the effect comes from the body's own nitrate recycling process.

When mouth bacteria are disrupted, blood pressure goes up regardless of how it's measured - whether at the doctor's office, at home, or with a 24-hour monitor.

The link between oral bacteria that convert nitrates to nitrites and blood pressure is stronger in people who don't have high blood pressure already.